The spring issue of Ms. magazine-on newsstands 4/29/08 -includes a provocative look at women and insomnia . Gayle Greene-author of the recent book Insomniac and a professor at Scripps College in California -points out that nearly half again as many women as men complain that they can't sleep. Yet 75 percent of sleep research has been done on men.

"As with other conditions that affect more women than men," writes Greene, "there's been a tendency to assume that the problem is psychological." Not so, she insists. While stress can lead to insomnia-and women are undoubtedly under stress juggling work, marriage and motherhood-researchers should take a better look at the crucial connections between female physiology and sleep.

Girls' insomnia exceeds boys only after puberty-when surges of estrogen and progesterone make sleep more vulnerable. Menopause is another trouble spot for women's sleep, with researchers suspecting that fluctuations in hormones-not just their depletion-may be the culprit. Women also have problems sleeping just after giving birth, when estrogen plummets from its high point during pregnancy.

Greene points out that it's always easier to psychologize the problem than do the hard work of finding out what's really going on. "Since insomnia disproportionately affects women, its neglect by researchers is our neglect," she writes.